An unexpected clade of South American ground beetles (Coleoptera, Carabidae, Bembidion).

Maddison DR - Zookeys (2014)

Bottom Line:
Redefined subgenera within the complex are each well-supported as monophyletic.Most striking was the discovery that a small set of morphologically and ecologically heterogeneous species formed a clade, here called subgenus Nothonepha.A revised classification is proposed for the Antiperyphanes Complex.

ABSTRACTPhylogenetic relationships of the Antiperyphanes Complex of the genus Bembidion are inferred using DNA sequences from seven genes (two nuclear ribosomal, four nuclear protein coding, and one mitochondrial protein coding). Redefined subgenera within the complex are each well-supported as monophyletic. Most striking was the discovery that a small set of morphologically and ecologically heterogeneous species formed a clade, here called subgenus Nothonepha. This unexpected result was corroborated by the discovery of deep pits in the lateral body wall (in the mesepisternum) of all Nothonepha, a trait unique within Bembidion. These pits are filled with a waxy substance in ethanol-preserved specimens. In one newly discovered species (Bembidion tetrapholeon sp. n., described here), these pits are so deep that their projections into the body cavity from the two sides touch each other internally. These structures in Bembidion (Nothonepha) are compared to very similar mesepisternal pits which have convergently evolved in two other groups of carabid beetles. The function of these thoracic pits is unknown. Most members of subgenus Nothonepha have in addition similar but smaller pits in the abdomen. A revised classification is proposed for the Antiperyphanes Complex.

Mentions:
Internally these abdominal pits are evident as knob-shaped intrusions (Fig. 14A, C). Consistent with the lack of externally visible pits, Bembidion lonae lacks these intrusions, and has instead only a ridge between the abdominal segments (Fig. 14D), as is typical in Bembidion.

Mentions:
Internally these abdominal pits are evident as knob-shaped intrusions (Fig. 14A, C). Consistent with the lack of externally visible pits, Bembidion lonae lacks these intrusions, and has instead only a ridge between the abdominal segments (Fig. 14D), as is typical in Bembidion.

Bottom Line:
Redefined subgenera within the complex are each well-supported as monophyletic.Most striking was the discovery that a small set of morphologically and ecologically heterogeneous species formed a clade, here called subgenus Nothonepha.A revised classification is proposed for the Antiperyphanes Complex.

ABSTRACTPhylogenetic relationships of the Antiperyphanes Complex of the genus Bembidion are inferred using DNA sequences from seven genes (two nuclear ribosomal, four nuclear protein coding, and one mitochondrial protein coding). Redefined subgenera within the complex are each well-supported as monophyletic. Most striking was the discovery that a small set of morphologically and ecologically heterogeneous species formed a clade, here called subgenus Nothonepha. This unexpected result was corroborated by the discovery of deep pits in the lateral body wall (in the mesepisternum) of all Nothonepha, a trait unique within Bembidion. These pits are filled with a waxy substance in ethanol-preserved specimens. In one newly discovered species (Bembidion tetrapholeon sp. n., described here), these pits are so deep that their projections into the body cavity from the two sides touch each other internally. These structures in Bembidion (Nothonepha) are compared to very similar mesepisternal pits which have convergently evolved in two other groups of carabid beetles. The function of these thoracic pits is unknown. Most members of subgenus Nothonepha have in addition similar but smaller pits in the abdomen. A revised classification is proposed for the Antiperyphanes Complex.